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用600℃时效微观组织变化和冲击韧性的变化评价了1Cr21Ni5Ti双相不锈钢的稳定性。结果表明：1Cr21Ni5Ti双相不锈钢稳定性对Ti/C极为敏感,低Ti/C（Ti/C=4.08）钢600℃时效快速析出富Cr的M23C6碳化物,降低奥氏体内的Cr和C含量致使时效后冷却过程中奥氏体转变为马氏体,并伴随着冲击韧性的严重恶化;而Ti/C适度的钢明显抑制了M23C6碳化物的析出和随后奥氏体向马氏体转变,长时间时效后冲击韧性高出低Ti/C钢近一倍。

Microstructural Stability and Its Influence on Impact Energy in 1Cr21Ni5Ti Duplex Stainless Steel

The stability of 1Cr21Ni5Ti duplex stainless steel, aged at 600oC, has been evaluated through the microstructural evolution and impact energy change. The results have indicated that the stability of 1Cr21Ni5Ti duplex stainless steel was highly sensitive to ratio of Ti/C. Due to rapid precipitation of Cr rich M23C6 carbide in the steel with lower Ti/C (Ti/C=4.08), Cr and C contents in austenitic phase had reduced to such low levels that the austenitic phase transformed to martensite on cooling from aging temperature to ambient temperature, led to the impact energy deteriorating. In contrast, Cr rich M23C6 carbide precipitation had been depressed in the steel with moderate Ti/C (Ti/C=5.21), and accordingly, austenite transformation to martensite had been arrested on cooling from aging temperature. Finally, after long time aging the impact energy of the steel with Ti/C=5.21 is nearly two times that of steel with Ti/C=4.08.